T cells are involved in the pathogenesis of atherosclerosis. We aimed to search for any association between the peripheral T-cell activities and atherogenic risk factors in healthy subjects. Fifty male volunteers (age 22.0 +/- 2.4 years) were enrolled. No subject had any chronic disease or was under any drug treatment. Lymphocytes were isolated from heparinized venous blood and the proliferative responses to phytohemagglutinin (PHA) were measured from the amount of radioactive thymidine uptake by the lymphocyte DNA. T-cell activity responses of patients with a family history of coronary events were compared with others. The activity responses of smokers were compared with nonsmokers. Subjects with a positive family history of coronary events had higher PHA stimulated T-cell response and delta cpm (P < 0.05 for each). Total and low-density lipoprotein cholesterol levels of the subjects with a positive family history of cardiovascular events were positively correlated with the PHA-activated T-cell responses (P = 0.022, r = 0.604 and P = 0.015, r = 0.635, respectively). There was no significant difference between the T-cell activity responses of smokers and nonsmokers. No correlation was found between the biochemical parameters and T-cell activities in these groups. Peripheral T-cell activity responses to PHA are higher in the asymptomatic relatives of patients with coronary events. This may be a clue for the familial tendency of atherosclerotic diseases. Further follow-up studies are necessary to investigate the relationship.